There’s a famous Norman Rockwell painting titled “Freedom of Speech,” depicting an idealized American town meeting. The painting, part of a series illustrating F.D.R.’s “Four Freedoms,” shows an ordinary citizen expressing an unpopular opinion. His neighbors obviously don’t like what he’s saying, but they’re letting him speak his mind.

That’s a far cry from what has been happening at recent town halls, where angry protesters — some of them, with no apparent sense of irony, shouting “This is America!” — have been drowning out, and in some cases threatening, members of Congress trying to talk about health reform.

Some commentators have tried to play down the mob aspect of these scenes, likening the campaign against health reform to the campaign against Social Security privatization back in 2005. But there’s no comparison. I’ve gone through many news reports from 2005, and while anti-privatization activists were sometimes raucous and rude, I can’t find any examples of congressmen shouted down, congressmen hanged in effigy, congressmen surrounded and followed by taunting crowds.

And I can’t find any counterpart to the death threats at least one congressman has received.

So this is something new and ugly. What’s behind it?

Robert Gibbs, the White House press secretary, has compared the scenes at health care town halls to the “Brooks Brothers riot” in 2000 — the demonstration that disrupted the vote count in Miami and arguably helped send George W. Bush to the White House. Portrayed at the time as local protesters, many of the rioters were actually G.O.P. staffers flown in from Washington.

But Mr. Gibbs is probably only half right. Yes, well-heeled interest groups are helping to organize the town hall mobs. Key organizers include two Astroturf (fake grass-roots) organizations: FreedomWorks, run by the former House majority leader Dick Armey, and a new organization called Conservatives for Patients’ Rights.

The latter group, by the way, is run by Rick Scott, the former head of Columbia/HCA, a for-profit hospital chain. Mr. Scott was forced out of that job amid a fraud investigation; the company eventually pleaded guilty to charges of overbilling state and federal health plans, paying $1.7 billion — yes, that’s “billion” — in fines. You can’t make this stuff up.

But while the organizers are as crass as they come, I haven’t seen any evidence that the people disrupting those town halls are Florida-style rent-a-mobs. For the most part, the protesters appear to be genuinely angry. The question is, what are they angry about?

There was a telling incident at a town hall held by Representative Gene Green, D-Tex. An activist turned to his fellow attendees and asked if they “oppose any form of socialized or government-run health care.” Nearly all did. Then Representative Green asked how many of those present were on Medicare. Almost half raised their hands.

Now, people who don’t know that Medicare is a government program probably aren’t reacting to what President Obama is actually proposing. They may believe some of the disinformation opponents of health care reform are spreading, like the claim that the Obama plan will lead to euthanasia for the elderly. (That particular claim is coming straight from House Republican leaders.) But they’re probably reacting less to what Mr. Obama is doing, or even to what they’ve heard about what he’s doing, than to who he is.

That is, the driving force behind the town hall mobs is probably the same cultural and racial anxiety that’s behind the “birther” movement, which denies Mr. Obama’s citizenship. Senator Dick Durbin has suggested that the birthers and the health care protesters are one and the same; we don’t know how many of the protesters are birthers, but it wouldn’t be surprising if it’s a substantial fraction.

And cynical political operators are exploiting that anxiety to further the economic interests of their backers.

Does this sound familiar? It should: it’s a strategy that has played a central role in American politics ever since Richard Nixon realized that he could advance Republican fortunes by appealing to the racial fears of working-class whites.

Many people hoped that last year’s election would mark the end of the “angry white voter” era in America. Indeed, voters who can be swayed by appeals to cultural and racial fear are a declining share of the electorate.

But right now Mr. Obama’s backers seem to lack all conviction, perhaps because the prosaic reality of his administration isn’t living up to their dreams of transformation. Meanwhile, the angry right is filled with a passionate intensity.

And if Mr. Obama can’t recapture some of the passion of 2008, can’t inspire his supporters to stand up and be heard, health care reform may well fail.